1. Field of the Invention
The present invention relates to an electrostatic recording apparatus. More specifically, the present invention relates to an electrostatic recording apparatus in which electrostatic latent images of two or more gradations having voltages different from each other are formed on a photosensitive member at essentially the same time and respective electrostatic latent images are developed with toners different in color from each other.
2. Description of the Prior Art
One example of this kind of an electrostatic recording apparatus is disclosed in, for example, Japanese Patent Laying-Open No. 55-59473 laid-open on May 2, 1980. In this prior art, a photosensitive drum having a surface insulating layer is uniformly charged in a first polarity by a first charger, and then, the photosensitive drum is charged by a second charger in a second polarity opposite to the first polarity. Light images having light intensity different from each other are simultaneously irradiated onto the photosensitive drum being charged by the second charger by a first exposing means so as to form electrostatic latent images of two gradations thereon. Thereafter, the photosensitive drum is wholly exposed such that two electrostatic latent images, one of which has a voltage of the positive polarity (+) and the other of which has a voltage of the negative polarity (-) can be simultaneously formed on the photosensitive drum. Then, respective electrostatic latent images are developed with different color toners which are charged in opposite polarities with each other. Thus, in the above described prior art, by developing the two electrostatic latent images at the substantive same time with the different color toners, a two-color toner image can be obtained. However, in the prior art, since it is necessary to wholly expose the photosensitive drum prior to a developing step, there is a problem that such a process becomes complex.